Electric current relays often arc upon opening a closed relay. To avoid problems caused by arcing, relays are often spring-loaded to rapidly separate the poles when the relays are opened and sometimes to rapidly close the poles when the relays are closed.
Continued operation of the relays may build deposits on or rearrange material of the relay poles, promoting arcing and eventually fusing and welding the poles shut. The continued closed condition of one or two or more relays necessary for completing a circuit may not be noticeable, because the relays are often covered and because multiple moving parts in the relays may hide the condition of unwanted permanent closure of one of the relays. Under that condition one functioning relay may make or break the circuit which is intended to be made or broken by two relays.
Needs exist for improved relay operations.